The operator's compartment of most vehicles, such as Class 8 trucks, generally include control switches that are in communication with a variety of electrical systems. In a current typical system, actuation of the switch produces a relatively high current which is capable of breaking through the resistance of corrosion, oxidation, and contaminants that may have formed on the contacts. However, modern electronic applications, such as computers, do not require high current. Computers generally employ very low current output to activate the switching action of a larger driver circuit. Such driver circuits are used to actuate a variety of systems, such as turn signals or cruise control of the vehicle. Low current switches are much more susceptible to environmental contamination.
Switches currently available for such systems are typically exposed contact switches. Contact switches generally include a lever and attached, plated or unplated, copper contacts that may be directly actuated into and out of physical contact with corresponding contacts of the driver circuit. In a typical arrangement, the lever extends from within a housing disposed within the steering column control stalk of the vehicle. Displacement of the lever causes the lever contact to be displaced into contact with the driver circuit contact located within the housing. Contact between the lever contact and the driver circuit contact results in a closed circuit, thereby actuating the turn signal or some other feature of the vehicle. Although such switches are effective at changing the state of a switch, they are not without their problems.
First, because physical contact between the lever contact and circuit contact is required to close the circuit, and the contacts are exposed to the environment, such switches often suffer high rates of failure. Additionally, reliability is also compromised due to frictional contact and wear on pivoting and detenting features. Debris or corrosion may build up at the contact points between the lever contact and the circuit contact, thereby causing an unintended and undesirable increase in impedance of the switch. Such corrosion also decreases the useful life of the switch. Finally, such switches are relatively expensive to manufacture due to the complexity of the contact arrangements and the need to switch relatively high current.
Thus, there exists a need for a contactless switch that is economical to manufacture, has a high degree of reliability and meets the performance expectations of the end user.